This invention relates to a method for reducing the fuel consumption of an internal combustion engine.
There has been considerable effort in recent years to improve the fuel economy of motor vehicles. This effort has no doubt received impetus from the increasing public awareness of the need for energy conservation. Such need having developed from a combination of factors with the most significant being the unavailability of adequate fuel supplies during times of certain unsettling world events and the general increase in fuel prices over the past several years.
To date, the main approach to obtain improved fuel economy has been a mechanical one, i.e., smaller cars and smaller engines. Another approach to reduce fuel consumption which has received a fair amount of attention recently has been the development of lubricants that reduce engine friction and thus reduce energy requirements. Among the lubricating oils which have been developed to solve the problem of energy losses due to high friction are the synthetic ester base oils which are generally expensive. Other lubricating oils have incorporated additives to reduce overall friction. Some of the additives used in lubricating oils include the esters of fatty acid dimers and glycols as disclosed in U.S. Pat. No. 4,105,571, the esters of monocarboxylic acids and glycerol as disclosed in U.S. Pat. No. 4,304,678, the esters of dimer acids and monohydric alcohol disclosed in U.S. Pat. No. 4,167,486, the esters of glycerol and monocarboxylic fatty acids as disclosed in U.K. Pat. Nos. 2,038,355 and 2,038,356 and esters of monocarboxylic fatty acids and polyhydric alcohols disclosed in U.S. Pat. No. 3,933,659.
Another group of additives which has been used in lubricating oils to reduce friction are the molybdenum containing compounds including insoluble molybdenum sulfides, organo molybdenum complexes, e.g., molybdenum amine complexes disclosed in U.S. Pat. No. 4,164,473, molybdenum thio-bis phenol complexes disclosed in U.S. Pat. Nos. 4,192,753, 4,201,683 and 4,248,720, molybdenum oxazoline complexes disclosed in U.S. Pat. No. 4,176,074 and molydenum lactone oxazoline complexes disclosed in U.S. Pat. No. 4,176,073.
Some of the above friction reducing additives have been suggested for use in hydrocarbon compositions such as fuels and other additives have been suggested for use in hydrocarbon compositions such as fuels and lubricating oils to improve lubricity and load carrying properties. While many of such additives do in fact satisfy some of the property requirements as suggested, it is also known that in many instances other problems arise such as additive burn up and decomposition as fuels go through the combustion zone and the actual improvement in properties such as friction reduction and fuel economy never materializes. Therefore, the use of different additives in lubricating oils to reduce friction does not suggest a method of improving fuel economy by changing or adding materials to the fuel composition itself. Accordingly, there is the need for additional methods to improve the fuel economy of an internal combustion engine used to power automotive vehicles.